StateMessage

local StateMessage = require("encompass").StateMessage

In certain cases, you may want to be able to broadcast information about the state of the game to multiple Modifiers without it being consumed by any one Modifiers in particular. StateMessage exists for this reason.

When a StateMessage is created, it is visible to all Modifiers that track its prototype.

Defining any logic on a StateMessage is an anti-pattern. Do not do this.

Function Reference

StateMessage.define(name, required_field_types, optional_field_types)

Arguments:

• name (string) – The name of the StateMessage prototype.
• required_field_types (table) – A table where the keys are field names and the values are types. If one of these fields is missing when the StateMessage is instantiated, or a field is passed to the message with an incorrect type, an error is thrown.
• optional_field_types (table) – A table where the keys are field names and the values are types. If a field is passed to the message with an incorrect type, an error is thrown.

Returns:

A new StateMessage prototype.

Example

time_dilation_state_message.lua

local StateMessage = require('lib.encompass').StateMessage

return StateMessage.define(
    'TimeDilationStateMessage',
    {
        factor = 'number'
    }
)

music_modifier.lua

local MusicMessage = require('hyperspace.messages.music')
local TimeDilationStateMessage = require('hyperspace.messages.state.time_dilation')

local ComponentModifier = require('lib.encompass').ComponentModifier
local MusicModifier = ComponentModifier.define(
    'MusicModifier',
    MusicMessage,
    { TimeDilationStateMessage }
)

function MusicModifier:modify(music_component, frozen_fields, message, dt)
    local time_dilation_state_message = self:get_state_message(TimeDilationStateMessage)

    local factor = 1
    if time_dilation_state_message ~= nil then
        factor = time_dilation_state_message.factor
    end

    dt = dt * factor

    local source = frozen_fields.source
    source:setPitch(factor)
    music_component.time = frozen_fields.time + dt
end

return MusicModifier